hb .15 ... what % castor needed ?
Got hold of a NIB HB .15 this morning. Before running it, I tore it down to check the innards. No swarf, dirt, or even a sign of dust or other foreign matter. Also beautiful machine work. (things are looking up.) Then, the big end of the con-rod caught my eye. It is unbushed. I have been using 15% Omega, with 4 OZs, per gallon, of castor added, (Comes out 'bout 19% oil, with castor making up 'bout 41% of the total oil content.) on my old baffled, cast iron piston Enyas. Planned on using the same fuel on the HB, but that unbushed rod has me concerned. Re-assembled the engine, & mounted it on the test stand. No instruction sheet, so took a guess at the prop size (7x4.5). Compression was "sky high" so I started with 5% nitro. That rod had me concened, so I went with 25% castor. I found a few threads where advice was given to use castor because of the cast Iron piston, but no-one even mentioned the unbushed rod. Maybe I'm overly concerned. Anyone have any experince with fueling this engine? Anyhow, I fired the thing up (third flip), got the needle close, let it run a few min., then twicked the needle a tad, & made a WOT rpm check. Got 16,200, so I feel that the prop is definetely in the ball park. Home for this engine is gonna be an original Lil' Extra. (The last two Counterfit Lil'Extras that I bought were very tail heavy with a lite engine mounted. The HB is only 5 & 1/8 OZs, so should do well in the "better balanced" original unit. Besides the fuel thing, I'd also like to know where (RPM) these things like to be run. I'm feelin pretty comfortable at the 16K area, but that may change when I get some response from you guys. ............. George K.